Overview

• The fifth WMO Air Quality and Climate Bulletin finds 2024 wildfire smoke drove above‑average PM2.5 in the Amazon basin, Canada, Siberia and Central Africa, with the Amazon showing the largest increase.
• WMO scientists report Canadian fires transported pollution to Europe last year and again this year when weather patterns aligned, demonstrating intercontinental reach.
• Fine PM2.5 particles can penetrate deeply into the lungs and cardiovascular system, and WHO links ambient air pollution to more than 4.5 million premature deaths annually.
• The bulletin highlights worsening winter smog on the Indo‑Gangetic Plain, tied to agricultural biomass burning in a region home to over 900 million people.
• Eastern China continues a multi‑year decline in PM2.5 that WMO attributes to sustained policies, underscoring that targeted actions can measurably improve air quality.